Apparatus for photographic processing

ABSTRACT

A drum photographic processer is provided to rotate horizontally but to be tilted to evacuate processing solution while still being rotated. The direction of rotation may be changed as well as the degree of tilting. A longitudinal slot within the drum serves to engage a leading edge of photographic film being processed and to assist in the desired flow of processing solution. Various devices to cause automatic evacuation of processing solution or tilting the drum are described.

United States Patent Wilkinson [54] APPARATUS FOR PHOTOGRAPHIC PROCESSING [72] Inventor: Peter R. S. Wilkinson, 2 Glade Close, Ditton Hill, Surbiton, Surrey,

England [22] Filed: May 26, 1970 1211 Appl. No.2 40,670

[30] Foreign Application Priority Data June 4, 1969 Great Britain ..28,217/69 52 US. c1. ..9s/93, 95/99 [51] Int. Cl. ..G03d 3/08 [58] Field of Search..; ..95/89 R, 93, 96, 97, 98, 99

[56] References Cited UNITED STATES PATENTS 3,550,521 12/1970 Carrie ..95/93 3,589,264 6/1971 Jensen ..95/93 3,381,599 5/1968 Banks ..95/93 X 3,517,600 6/1970 Woollacott ..95/89 2,947,236 8/1960 Siegel ..95/93 3,437,030 4/1969 -Mastrosimone et a1. ..95/93 FOREIGN PATENTS OR APPLICATIONS 1,549,183 11/1968 France ..95/93 Primary Examiner-Samuel S. Matthews Assistant Examiner-Fred L. Braun Attomey-Wolfe, Hubbard, Leydig, Voit & Osann 1571 ABSTRACT A drum photographic processer is provided to rotate horizontally but to be tilted to evacuate processing 1 solution while still being rotated. The direction of rotation may be changed as well as the degree of tilting. A longitudinal slot within the drum serves to engage a leading edge of photographic film being processed and to assist in the desired "flow of processing solution. Various devices to cause automatic evacuation of processing solution or tilting the drum are described.

15 Chins, 13 Drawing Figures PATENTEDnnvza m2 I SHEET 1 [IF 6 Pmmmuvza m2 SHEET 3 BF 6 FIGS FIG.4

FIGS

APPARATUS FOR PHOTOGRAPHIC PROCFSSING This invention relates to a method of, andapparatus for the processing of photographic sheet materials.

. Usually photographic sheet materials, and more particularly photographic paper-based print materials and photographic film based materials such as x-ray film sheets and large transparencies, are processed either by immersion of the flat sheet in a succession of processing solutions contained in shallow baths, or by suspending the sheets to hang vertically in deep baths of processing solution, and providing means for transferring the suspended sheets from one bath to the next in a series or, in more recent sophisticated methods, by feeding the sheet materials via or over roller systems which are adapted to apply to the sheet materials the successive processing liquids. For processing of silver halide latent images to black-and-white records, it is usually sufficient for the processing sequence to comprise a developing bath and a fixing bath or an activating bath and a stabilizing bath optionally with intermediate and final wash stages. For the processing of color material a more complex series of liquid treatments may be involved.

Modern photographic materials are designed by the manufacturers to be as devoid of curl as possible atall stages before, during and after processing, i.e. such materials tend to adopt a flat sheet configuration. It has been found that, in consequence, if a said photographic sheet material is rolled to cylindrical form and introduced into a cylindrical vessel it will, by its natural tendency to revert to a flat condition, take up a flexed position in which it tends to lie in close contact with the cylindrical walls of the vessel and this position will be retained even during the processing of the sheet with processing liquids, i.e. when the sheet is wet. Use is made of this phenomenon in the present invention which provides a method of, and apparatus for, processing photographic sheet material whilst it lies in contact with the inner walls of a cylindrical processing vessel.

According to' one aspect of the present invention, there is provided a method of processing a sheet of latent image-bearing material including locating the sheet inside a rotary processing vessel for rotation therewith, said vessel having an inlet and an outlet for processing liquid and being disposed, in use, with its axis of rotation substantially horizontal, rotating the said vessel with a predetermined quantity of processing liquid therein, and draining the processing liquid from said vessel, via its outlet, by tilting said vessel without discontinuing its rotation.

Preferably, before and during the draining of said vessel, it is rotated in opposite angular senses, respectively. 1

According to another aspect of the present invention, there is provided photographic sheet material processing apparatus including a light-tight rotary processing vessel having an inlet and an outlet for processing liquid, said vessel having means for per,- mitting a latent image-bearing sheet of photographic material to be located therein, driving means for causing said vessel to rotate about a substantially horizontal axis, means for passing, via said inlet, processing liquid to act on said sheet while said vessel is rotating, means for collecting the processing liquid and draining it via ofFIG. 1,

said outlet, and tilting means for tilting said vessel to slope towards said outlet while maintaining rotation of said vessel.

Preferably, the driving means has a control for enabling the sense of rotation of said vessel to be reversed while it is being tilted.

The said vessel may be provided with a partition plate located near the said outlet and extending across the said vessel so as to leave at least one peripheral space through which in use processing liquidmay flow, there being collecting channel means leading from the or each said space to said outlet for conveying said liquid to said outlet.

Advantageously, the said vessel is readily removably mounted in a frame for pivotal movement relative thereto, the frame containing in operation a substantially constant temperature bath.

Optionally, the said tilting means is constituted by a manually operable lever.

In a preferred embodiment, there is provided means for imparting a relatively small slope to said vessel towards the outlet without operating said lever when it is required to process a small sheet of photographic material'located at the low point of the sloped vessel.

The bath may beprovided with heater means and a temperature probe adjacent the said heater means.

Preferably, when the apparatus is to be used for processing film, the interior of the vessel is provided with projections or an apertured liner to enable processing liquid to be in contact with both sides of the said sheet.

Alternatively, or additionally, the interior of the vessel may be provided with a frusto-conical portion adjacent the said outlet to provide a barrier for the processing liquid during normal, i.e. untilted rotation of said vessel.

Preferred embodiments of the apparatus of this invention are illustrated in the accompanying drawings, wherein:

FIG. 1 is a somewhat diagrammatic sectional view of the apparatus of this invention,

FIG. 2 is a sectional view taken along the place 2-2 FIG. 3 is afront elevation, partially broken away, of the apparatus of FIG. 1 in its tilted position.

FIGS. 4 & 5 are respective end and partial longitudinal sections of one embodiment of a liquid extraction device embodied in the apparatus of this invention,

FIGS. 6 & 7 respectively correspond to FIGS. 4 & 5, but illustrate a further embodiment;

FIGS. 8 & 9 respectively correspond to FIG. 4 & 5, but illustrate another embodiment,

FIG. 10 is an end section of the processing vessel of the apparatus of this invention showing a liner in position and holding photographic material,

FIG. 11 is a fragmentary elevation, partially broken away, of the vessel of FIG. 10,

FIG. 12 is a rear elevational view of the apparatus shown in FIG. 1, and

FIG. 13 is a front elevation, partially broken away, of i the apparatus of FIG. 1, showing its slightly tilted condition for handling small areas of photographic materiparatus including a substantially hollow cylindrical drum mounted for rotation about a substantially horizontal axis. The drum 20 is in use frictionally driven by a pair of rollers 21, at least one of which is adapted to be driven from a synchronous electric motor 22 by way of gearing 23 and shaft 24.

The drum 20 and rollers 21 are mounted in a casing 25 from which the drum 20 extends and is readily manually removable,and which is pivotally connected to a frame 26.

The frame 26 is substantially U-shaped in' section, has screw-adjustable levelling feet 27, and serves as a constant temperature bath, preferably a water bath. The rollers 21 extend into the bath and the shaft of one of them is provided with a radial projection 28 to serve as a stirrer.

The water bath is provided with a heater element 30 and a thermostatic temperature probe 31 adjacen v thereto and connected to a thermostat 32. a

The motor 22 is controlled by a switch 33 carried on a casing portion 29, which also carries a heater switch 29a. The casing 29 houses the motor 22 and is provided with motor cooling apertures 34. The motor 22 preferably rotates the drum 20 at 20 to 60 r.p.m. preferably about 45 r.p.m.

Pivotal movement of the casing 25 with drum 20 relative to the frame 26 is.effected by means of a manually operable actuating lever 35. The electric motor 22 being located in the casing portion 29 integral with the casing 25, the said pivotalmovement does not interfere with the rotation of the drum 20. To facilitate this pivotal movement, the right-hand end (as viewed) of the casing 25 is provided with a bevelled portion 36.

The drum 20 has a cap 37 which can be clamped thereto in a light-tight manner by means of toggle clamps 38. The cap 37 has an elbow-shaped inlet pipe 39 extending therethrough which at its other end can co-operate with a funnel (not shown). The cap 37 is formed of two elements 40 and 42 secured together. The right-hand facing (as viewed) face 40 of the cap 37 is formed with a plurality of projecting and re-entrant surfaces 41 which are spaced uniformly from the'complementarily shaped end face of the element 42. The

gap between the surfaces of 40 and 42 provides a liquid flow path and simultaneously eliminates the risk of stray light entering the interior of the drum 20.

The other end of the drum is provided with a liquid extraction device which may be of many different kinds described below. Centrally, an extractor tube 43 is provided, and the frame 26 has an overflow pipe 44.

The exterior of the drum is preferably provided with annular knurled bands 45 for improved frictional engagement with the rollers 21. The interior of the drum has a longitudinally extending slat 46 which is provided with a screw clamp 46a for clamping the edges of has, extending therethrough, a plunger 49 which actuates a microswitch 50, the plunger 49 co-operating with a horizontally extending by-pass lever 52 of the frame 26. The arrangement is such that in the FIG. 1 position, the motor 22 drives the rollers 21 in a given angular sense, but on actuation of the lever 35, the roller 47 lifts the casing portion 29 and thus raises the plunger 49, whereby the motor 22 is reversed, and thus so also are the rollers 21.

The by-pass lever 52 has a finger piece 53 at one end, and at its other end is pivoted at 55. Approximately midway of the lever there is provided a dimple 51, centrally located, and a block 54 offset with respect to the dimple, the arrangement being such that the plunger 49 can rest severally on the block 54, in the dimple 51, and on the surface of the lever. As can be seen in FIGS. 12 and 13, the by-pass lever 52 has three positions respectively corresponding to normal or non by-pass, a

wash and small print positions, the latter being shown in FIG. 13 with a small-sized print 56. When the lever is in normal position the plunger. 49 is depressed by the surface of the lever so that the motor runs as required for processing. In the wash position the plunger drops onto the dimple 51 which operates the rnicrosvvitch to reverse the motor. In the small print position the block 54 is brought beneath the plunger 49 so depressing the plunger and maintaining the motor driving in the processing direction. The drum 20 is, as indicated, tilted by the block 54. The wash" position is for prolonged washing, where the full tilt of lever 35 is clearly unnecessary.

Referring now to FIGS. 4 to 9, several different embodiments of a liquid extractor device are shown. In FIGS. 4 to 9, the devices shown are effective when the motor 22 is reversed. v

In FIGS. 4 and 5 an obliquely or chordally extending partition plate 57 is provided across the interior of the drum 20. Between the plate 57 and the tube 43 a first curved guide member 58 and 59 are located. The first curved guidelmember 58 extends concavely inward from a point on the wall'of the drum 20 to a position spaced from a second point on the wall of the drum to provide a first channel 60 along the periphery of the drum through which the processing liquid may'flow. The second curved guide member 59 extends concavely inward from a point on the inner surface of the first curved guide member 58' to a position spaced from a second point on the inner surface of the first curved guide member to provide a second channel 61 along the inner surface of the first curved guide member. When the drum 20 rotates clockwise (as viewed) any liquid passing over the plate 57 simply flows back again. However, on tilting the drum 20, as shown in FIG. 3, and reversing the motor 22, the liquid passing over the plate 57 flows through the first channel 60 between the member 58 and the wall of the drum 20 and then through the second channel 61 between the members 58 and 59 to the outlet 43.

In FIGS. 6 and 7 the plate is in the form of a spiral pathway 62, but otherwise the principle of operation is the same as in FIGS. 4 and 5.

In FIGS. 8 and 9 there are four separate collector systems feeding through separate lines, respectively, the single outlet tube 43. Here the plate 63 has four peripheral gaps 64 between itself and the drum 20, and

four sets of guide members 65, 66 to feed the liquid to a respective outlet tube 67 feeding the single final outlet tube 43. Each collecting system comprising a first curved guide member 66 enclosing each of the separate tubes 67 and extending concavely inward from a point one on the wall of the drum to a position spaced from a second point on the wall of the drum to provide a first channel along the periphery of the drum through which the processing liquid may flow in response to a counterclockwise rotation of the drum 20 and a second curved guide member 65 cooperating with the first curved guide member 66 to enclose each of the tubes 67 and which extends concavely inward from a point on the inner surface of the member 66 to a position spaced from a second point on the inner surface of the member 66 to provide a second channel along the inner surface of the member 66 through which the processing liquid may HOW to the associated tube 67 and out of the drum through the outlet 43 in response to a counterclockwise rotation of the drum 20.

The interior of the drum may be ribbed to allow access of the processing liquid to the back of the sheet. However, as shown in FIGS. and 11, this is preferably achieved by inserting a flexible grid-like liner 69 into the drum 20.

As a variation, the drum 20 may be loaded with film carried on conventional spiral holders.

in use, the drum 20 is loaded, with the help of slat 46, with latent image bearing photographic sheet material 70 in a dark room, the cap 37 replaced to allow normal illumination of the room, and then the drum 20 is placed on the rollers 21; the heater element 30 having previously heated the bath a predetermined temperature, which is normally a few degrees F above the desired operating temperature. The motor 22 is now switched on and processing liquid is introduced into the drum via the inlet pipe 39. Only a small quantity of such liquid is required owing to the rotation of the drum 20 which also ensures uniform and even distributionof liquid over the sheet 70. After a certain time, the lever 35 is actuated to drain the said liquid from the drum 20 while the latter is reversed in rotation.

ln a modification, the motor 22 may be a variable speed motor since with a given photographic material difference speed of rotation and therefore different degrees of agitation) may be used to effect some control over the photographic contrast of the processed image.

It will be appreciated that the illustrated embodiments of this invention provide a simple and inexpensive method of and apparatus for the processing of photographic sheet material which enables rapid processing under completely controlled conditions while at the same time economic of the amount of processing liquid used.

I claim as my invention:

l. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outletdisposed at one end of said vessel for draining processing liquid from said vessel, said outlet being spaced radially inwardly away from the side walls of said vessel, reversible driving means for causing said vessel to rotate in either a predetermined first direction or a second direction opposite to said predetermined first direction about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent image-bearing sheet of photographic material located in said vessel while said vessel is rotating in said predetemrined first direction, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet in response to the rotation of said vessel in said second direction, said extractor being ineffective when said vessel is rotated in said first direction, and means fortilting said vessel to slope towards said liquid extractor and said cooperating outlet while said vessl' is rotating in said second direction whereby the liquid is extracted when said vessel is rotated in said second direction and not when said vessel is rotated in said first direction.

2. Apparatus as claimed in claim 1 wherein the driving means has a control for enabling the direction of rotation of said vessel to be reversed while it is being tilted.

3. Apparatus according to claim 1 wherein the vessel has a longitudinal slat projection on its inner surface.

4. Apparatus as claimed in claim 1 wherein the said vessel is provided with a partition plate located near the said outlet and extending across the said vessel so as to leave at least one peripheral space through which processing liquid may flow, there being collecting channel means leading from said at least one space to said outlet for conveying 'said liquid to said outlet.

5. Apparatus as claimed in claim 1 wherein the said vessel is readily removably mounted in a frame for pivotal movement relative thereto, the frame containing in operation a substantially constant temperature bath.

6. Apparatus as claimed in claim 5 wherein the bath is provided with heater means and a temperature probe adjacent the said heater means.

7. Apparatus as claimed in claim 1 wherein the said tilting means is constituted by a manually operable lever. I

8. Apparatus as claimed in claim 7 wherein there is provided means for imparting a relatively small slope to said vessel towards the outlet without operating said lever.

9. Apparatus as claimed in claim 1 wherein the interior of the. vessel is provided with projections or an apertured liner to enable processing liquid to be in contact with both sides of the said sheet.

10. Apparatus as claimed in claim 1 wherein bypass means is provided for selectively by-passing the tilting means and for tilting the said vessel to a lesser extent than the tilting means.

11. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outlet disposed at one end of said vessel for draining processing liquid from said vessel, driving means for causing said vessel to rotate about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent imagebearing sheet of photographic material located in said vessel while said vessel is rotating, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet, means for tilting said vessel to slope towards said liquid extractor and said cooperating outlet while maintaining the rotation of said vessel, and bypass means to selectively bypass the tilting means and to tilt said vessel, to a lesser extent than said tilting means, including a manually operated threeposition lever in the first position of which the bypass means is inoperative, in the second position the driving means is actuated to reverse the direction of rotation of the vessel for use when a prolonged wash is required, and in the third position the tilting means is bypassed to reduce the extent of tilting so as to permit processing of a small-sized sheet of photographic material in an economical manner.

12. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outlet disposed at one end of said vesselv for draining processing liquid from said vessel, driving means for causing said vessel to rotate about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent imagebearing sheet of photographic material located in said vessel while said vessel is rotating, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet, said liquid extractor comprising a partition plate which extends chordally across the interior of said vessel to provide at least one peripheral space through which the processing liquid may flow to a plurality of collecting means which channel said processing liquid toward said cooperating outlet in response to rotation of the vessel in a predetermined direction so that said processing liquid drains out of said vessel through said outlet and means for tilting said vessel to slope towards said liquid extractor and said cooperating outlet while maintaining the rotation of said vessel.

13. Apparatus as claimed in claim 12 wherein the plurality of collecting means comprises a first curved guide member extending concavely inward from a point on the wall of the vessel to a position spaced from a second point on the wall of the vessel to provide a first channel along the periphery of the vessel through which the processing liquid may flow and a second curved guide member extending concavely inward from a point on the inner surface of said first curved member to a position spaced from a second point on the inner surface of said first curved member to provide a second channel along the inner surface of said first curved member through which the processing liquid may flow to the cooperating outlet. y

'14. Apparatus as claimed in claim 12 wherein the plurality of collecting means comprises an inwardly spiralling member attached at one end to the wall of the vessel and having its other end positioned about the axis of the cooperating outlet.

15. Apparatus as claimed in claim 12 wherein the outlet comprises a plurality of tubes and the liquid extractor cooperating with the outlet comprises apartition plate which extends chordally across the interior of said vessel to provide a multiplicity of peripheral spaces through which the processing liquid may flow to separate collecting means associated with each tube; each of said collecting means comprising a first curved guide member enclosing each of said separate tubes and extending concavely inward from a point one on the wall of the vessel to a position spaced from a second point on the wall of the vessel to provide a first channel along the periphery of the vessel through which the processing liquid may How and a second curved guide member cooperating with said first curved guide member to enclose each of said tubes and extending concavely inward from a point on the inner surface of said first curved guide member to a position spaced from a second point on the inner surface of said first curved guide member to provide a second channel along the inner surface of said first curved guide member through which the processing liquid may fiow to the respective tube associated with each said separate collecting means. 

1. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outlet disposed at one end of said vessel for draining processing liquid from said vessel, said outlet being spaced radially inwardly away from the side walls of said vessel, reversible driving means for causing said vessel to rotate in either a predetermined first direction or a second direction opposite to said predetermined first direction about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent image-bearing sheet of photographic material located in said vessel while said vessel is rotating in said predetermined first direction, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet in response to the rotation of said vessel in said second direction, said extractor being ineffective when said vessel is rotated in said first direction, and means for tilting said vessel to slope towards said liquid extractor and said cooperating outlet while said vessl is rotating in said second direction whereby the liquid is extracted when said vessel is rotated in said second direction and not when said vessel is rotated in said first direction.
 2. Apparatus as claimed in claim 1 wherein the driving means has a control for enabling the direction of rotation of said vessel to be reversed while it is being tilted.
 3. Apparatus according to claim 1 wherein the vessel has a longitudinal slat projection on its inner surface.
 4. Apparatus as claimed in claim 1 wherein the said vessel is provided with a partition plate located near the said outlet and extending across the said vessel so as to leave at least one peripheral space through which processing liquid may flow, there being collecting channel means leading from said at least one space to said outlet for conveying said liquid to said outlet.
 5. Apparatus as claimed in claim 1 wherein the said vessel is readily removably mounted in a frame for pivotal movement relative thereto, the frame containing in operation a substantially constant temperature bath.
 6. Apparatus as claimed in claim 5 wherein the bath is provided with heater means and a temperature probe adjacent the said heater means.
 7. Apparatus as claimed in claim 1 wherein the said tilting means is constituted by a manually operable lever.
 8. Apparatus as claimed in claim 7 wherein there is provided means for imparting a relatively small slope to said vessel towards the outlet without operating said lever.
 9. Apparatus as claimed in claim 1 wherein the interior of the vessel is provided with projections or an apertured liner to enAble processing liquid to be in contact with both sides of the said sheet.
 10. Apparatus as claimed in claim 1 wherein bypass means is provided for selectively by-passing the tilting means and for tilting the said vessel to a lesser extent than the tilting means.
 11. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outlet disposed at one end of said vessel for draining processing liquid from said vessel, driving means for causing said vessel to rotate about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent image-bearing sheet of photographic material located in said vessel while said vessel is rotating, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet, means for tilting said vessel to slope towards said liquid extractor and said cooperating outlet while maintaining the rotation of said vessel, and bypass means to selectively bypass the tilting means and to tilt said vessel, to a lesser extent than said tilting means, including a manually operated three-position lever in the first position of which the bypass means is inoperative, in the second position the driving means is actuated to reverse the direction of rotation of the vessel for use when a prolonged wash is required, and in the third position the tilting means is bypassed to reduce the extent of tilting so as to permit processing of a small-sized sheet of photographic material in an economical manner.
 12. Photographic sheet material processing apparatus which comprises a light-tight rotary processing vessel having an inlet for adding processing liquid to said vessel and an outlet disposed at one end of said vessel for draining processing liquid from said vessel, driving means for causing said vessel to rotate about a substantially horizontal axis, means for adding, through said inlet, processing liquid to act on a latent image-bearing sheet of photographic material located in said vessel while said vessel is rotating, a liquid extractor in the vessel cooperating with said outlet for collecting the processing liquid and draining it out of said vessel through said outlet, said liquid extractor comprising a partition plate which extends chordally across the interior of said vessel to provide at least one peripheral space through which the processing liquid may flow to a plurality of collecting means which channel said processing liquid toward said cooperating outlet in response to rotation of the vessel in a predetermined direction so that said processing liquid drains out of said vessel through said outlet and means for tilting said vessel to slope towards said liquid extractor and said cooperating outlet while maintaining the rotation of said vessel.
 13. Apparatus as claimed in claim 12 wherein the plurality of collecting means comprises a first curved guide member extending concavely inward from a point on the wall of the vessel to a position spaced from a second point on the wall of the vessel to provide a first channel along the periphery of the vessel through which the processing liquid may flow and a second curved guide member extending concavely inward from a point on the inner surface of said first curved member to a position spaced from a second point on the inner surface of said first curved member to provide a second channel along the inner surface of said first curved member through which the processing liquid may flow to the cooperating outlet.
 14. Apparatus as claimed in claim 12 wherein the plurality of collecting means comprises an inwardly spiralling member attached at one end to the wall of the vessel and having its other end positioned about the axis of the cooperating outlet.
 15. Apparatus as claimed in claim 12 wherein the outlet comprises a plurality of tubes and the liquid extractor cooperating with the outLet comprises a partition plate which extends chordally across the interior of said vessel to provide a multiplicity of peripheral spaces through which the processing liquid may flow to separate collecting means associated with each tube; each of said collecting means comprising a first curved guide member enclosing each of said separate tubes and extending concavely inward from a point one on the wall of the vessel to a position spaced from a second point on the wall of the vessel to provide a first channel along the periphery of the vessel through which the processing liquid may flow and a second curved guide member cooperating with said first curved guide member to enclose each of said tubes and extending concavely inward from a point on the inner surface of said first curved guide member to a position spaced from a second point on the inner surface of said first curved guide member to provide a second channel along the inner surface of said first curved guide member through which the processing liquid may flow to the respective tube associated with each said separate collecting means. 